Odonata assemblages at two urban wetlands in West Bengal, India

Abstract

Adult Odonata represent valuable indicators of natural habitat quality, ecosystem integrity, and pollution status in freshwater ecosystems. This study aimed to investigate how varying climatic condition, sub-habitat types, and physicochemical ambience of wetlands impact Odonata diversity. We compared the abundance and richness of Odonata in two urban wetlands and their surrounding areas: Purulia Sahebbandh (PS) located amidst Purulia town and faced higher anthropogenic threats, and Adra Sahebbandh (AS) located in a slightly remote location. Sampling was conducted over a period of one year (December 2018 to November 2019) using the Pollard walk method and direct search technique. A total of 47 Odonata species were recorded, including 33 species of dragonflies (Anisoptera) and 14 species of damselflies (Zygoptera). AS exhibited significant higher overall abundance compared to PS, with the monsoon season showing the highest abundance in both wetlands. Water-associated vegetation zones harbored the highest species richness. Species richness and abundance significantly differed among most of the sub-habitat types. Physicochemical factors such as pH, electrical conductivity, salinity, nitrate and phosphate concentrations, and dissolved oxygen significantly influenced Odonata abundance and species richness. The urban location, pollution load, and lack of natural vegetation in PS’s surrounding areas likely contributed to the lower Odonata abundance. Implementing sustainable management measures for wetlands and their surroundings is crucial to enhancing ecosystem services and supporting Odonata populations.